(1) Field of the Invention
The present invention relates generally to a method and apparatus for removing combustion deposits from the surfaces of fossil fuel boilers, and in particular to a method and system to optimize sootblower operating parameters by measuring the effects of sootblowing operations, and adjusting the sootblower operating parameters used in subsequent sootblowing operations based upon the effects measured.
(2) Description of the Prior Art
The combustion of coal and other fossil fuels during the production of steam or power produces combustion deposits, i.e., slag, ash and/or soot, that accumulates on the surfaces in the boiler, decreasing boiler efficiency by reducing heat transfer. These deposits are periodically removed by directing a cleaning medium, e.g., air, steam, water or mixtures thereof, against the surfaces upon which the deposits accumulate with cleaning devices known generally in the art as sootblowers.
To completely eliminate the negative effects of combustion deposits on boiler efficiency, the boiler surfaces, and in particular the heat transfer tubes, would need to be essentially free of deposits at all times. However, the continuous cleaning that would be required to maintain this cleanliness would be prohibitively expensive. In addition, injection of the cleaning medium into the boiler reduces boiler efficiency and prematurely damages heat transfer surfaces if over cleaned. Boiler surfaces, and in particular heat transfer tubes, can also be damaged as a result of erosion by high velocity air or steam jets and/or thermal impact occurring by impinging a jet of relatively cool cleaning medium, especially air or liquid, onto a hot, clean surface. Therefore, it is equally important that these surfaces are not unnecessarily cleaned.
Sootblowers are normally operated on a time schedule based on past experience, or on measured boiler conditions, in particular the reduction of heat transfer by the heat transfer tubes. Boiler conditions may be determined by visual observation, by measuring boiler parameters, or by the use of sensors on the boiler surfaces to measure conditions indicative of the level of ash accumulation, e.g., heat transfer rate degradation. Numerous methods and apparatus have been described in the prior art for measuring boiler conditions, or for determining the optimum timing of sootblowing operations. Representative patents are: